B2.2 Size

Question 1

Surface area to volume ratio

Answer 1

Surface of an area per unit volume of an object

Question 2

Format surface area to volume ratio should be presented in

Answer 2

Ratio
Surface area : volume
It should be simplified so volume = 1cm³

Question 3

Why a tapeworm can rely upon diffusion alone to provide nutrients, where as multicellular organisms cannot

Answer 3

The larger the surface area to volume ratio the more easily and quickly nutrients can diffuse, as diffusion ratio is small e.g the tape worm

Increase size of organism = decrease surface area to volume ratio,
therefore diffusion distance becomes to great to allow an organism to meet the cells’ demands

Question 4

Examples of adaptations to animal cells to improve surface area to volume ratio

Answer 4

Villi - intestines

Microvilli - Cilliated epithelial cells lungs

Alveoli - spherical shape

Question 5

Adaptations to plants to increase surface area to volume ratio

Answer 5

Broad flat leaves - increase SA for capturing light & gaseous exchange via the stomata

Root hair cells

Question 6

Adaptations of the lungs to maximise the rate at which oxygen enters the body

Answer 6

Single cell wall
Ventilation moves air in and out of lungs to maintain concentration gradient
Capillary network means good blood supply, which maintains concentration gradient
Spherical shape increases surface area

Question 7

Adaptations of villi to maximise rate of diffusion and active transport in the small intestine

Answer 7

Single cell wall
Capillary network means good blood supply, which maintains concentration gradient
Fingerlike shape increases surface area
Microvilli increases surface area further
Many mitochondria to provide energy for active transport

Question 8

Why transport systems are needed

Answer 8

To transport a substance to where it is needed once it has diffused

Question 9

Transport systems in humans

Answer 9

Respiratory

Circulatory

Digestive

Endocrinology

Nervous

Urinary

Question 10

What is the circulatory system

Answer 10

Heart and blood vessels

Question 11

Circulatory system of a fish compared to human circulatory system

Answer 11

Fish have a single circulatory system, humans have a double circulatory system

Question 12

State difference between oxygenated and deoxygenated blood

Answer 12

Oxygenated = high levels of oxygen
Deoxygenated = low levels of oxygen

Question 13

Name the the three types of blood vessel shown below.
/ / /.:. ./ / /
◎ / ◎./ ◉/
[x2] [x2000] [x2]
A B C

Answer 13

A = vein
B = capillary
C = artery

Question 14

Name adaptations of the three blood vessels

Answer 14

Vein: thin outer wall, thin layer of muscle and elestic fibres, large lumen
Capillary: very small lumen, single cell wall
Artery: thick outer wall, thick layer of muscle and elestic fibres, small lumen

Question 15

Why humans have a double circulatory system

Answer 15

Consists of 2 circuits joined together
First circuit pumps deoxygenated blood to lungs to take in oxygen, and then returns oxygenated blood to heart
Second circuit pumps oxygenated blood all around the other organs of body and returns deoxygenated blood to heart

Question 16

Benefits of having a double circulatory system

Answer 16

Deoxygenated and oxygenated blood does not mix
Blood is under higher pressure as it does not have to travel as far
High pressure means the materials are transported around the body faster

Question 17

Difference between cardiac muscle and the muscles in the rest of your body

Answer 17

Heart is made of cardiac muscle that contracts without recieving nerve impulses from our brain
Muscle in the rest of your body (e.g in your arm) require a nervous signal to stimulate contraction

Question 18

Parts of a heart

. Pulmonary vein
I———————->LUNGS—————————
Pulmonary I ┌──────-─┬───────┐ I
Artery I | | | I
I————+ >│Right atrium │Left Atrium │<—I
I I ├───v────┼────v──┤
I I—-| | |—
Vena cava │Right Ventricle │ Left Ventricle | I
I └──────-─┴───────┘ I
L________________________BODY<____________________I
Aorta

Answer 18

. Pulmonary vein
I———————->LUNGS—————————
Pulmonary I ┌──────-─┬───────┐ I
Artery I | | | I
I————+ >│Right atrium │Left Atrium │<—I
I I ├───v────┼────v──┤
I I—-| | |—
Vena cava │Right Ventricle │ Left Ventricle | I
I └──────-─┴───────┘ I
L________________________BODY<____________________I
Aorta

Right side is deoxygenated
Left side is oxygen rich

Question 19

Pathway through the human circulatory system

Answer 19

Deoxygenated blood enters lungs
Oxygen enters blood - CO2 leaves
Blood enters heart through pulmonary vein, into the left atria
Blood is pumped through the heart from left artria to left ventricle, via bicuspid valve
Blood is pumped out of left ventricle through Aorta and goes to rest of the body
Oxygen diffuses out of the blood and CO2 diffuses in
Blood enters right atria of heart through vena cava
Blood is pumped through heart from right artria to right ventricle, via tricuspid valve
Blood is pumped out of right ventricle, to return to lungs via pulmonary artery

Question 20

4 key components of blood and their function

Answer 20

Red blood cells - small biconcave cells containing haemoglobin and have no nucleus to enable and maximise oxygen transport
Small in size, which guarantees passage even through tiny capillaries

White blood cells - large cells fight disease by making antibodies, or changing their shape to engulf pathogens

Platelets - tiny structures/fragments of cells that help blood to clot

Plasma - Made up of 90% water, fluid in which the other components of blood float within
Acts as a transport medium for digested food, waste products, hormones and antibodies

Question 21

Type of blood cell which is most common in the blood

Answer 21

Red blood cells

Question 22

Xylem

Answer 22

Transports water and mineral ions from roots to stem, leaves and flowers
End walls of dead xylem cells broken to allow water and dissolved minerals to move through

Question 23

Function of phloem

Answer 23

Transports dissolves sugars from photosynthesis, and other soluble food molecules from leaves to all other areas of the plant

Question 24

Structure formed by xylem and phloem within the plant

Answer 24

Vascular bundle

Question 25

What tissue makes up bulk of plant in woody plants like trees

Answer 25

Xylem

Question 26

Experiment that can be done to easily visualise the xylem in plant tissue

Answer 26

Place celery in a jug of water containing food colouring
Leave for 24 hours
Cut slice of celery and veiw using magnifiying glass or light microscope

Question 27

Structure of xylem

Answer 27

Made from dead cells
No cell walls at ends of cells
Dead cells form tubes for water and mineral ions to flow
Xylem cellulose cell wall is thickened and stiffened with lignin to provide support

Question 28

Structure of phloem

Answer 28

Made of living cells
Cell walls connecting these cells do not completely breakdown creating sieve plates
Sieve plates allow dissolved sugars to pass
Connected cells form a tube allowing dissolved sugers to be transported

Question 29

Direction of flow in xylem

Answer 29

One way - Roots to leaves

Question 30

Direction of flow in the phloem

Answer 30

Two-way / bidirectional

Question 31

Tissue in a plant which would transport glucose

Answer 31

Phloem

Question 32

If a cross section was taken through the plant in the stem, where would you expect vascular bundle to be found

Answer 32

Bundles organised spherically in the cortex: cross section of the stem
Larger phloem at top of the bundle with smaller xylem tubes underneath

Question 33

If a cross section was taken through the plant in the root, where would you expect the vascular bundle to be found

Answer 33

Bundle in the centre of the root
Xylem in the centre of the bundle
Phloem around the outside of the xylem
Surrounded by ground tissue

Question 34

If a cross section was taken through the plant in the leaf, where would you expect the vascular bundle to be found

Answer 34

In spongy mesophyll layer
Xylem closest to palisade mesophyll layer (towards top of the leaf)
Phloem closest to the lower epidermis

Question 35

How vascular bundles provide support

Answer 35

In the leaf they form a network that supports softer tissue
In the stem they are loacted around the outer edge providing the stem with strength to resit bending
In the root they are found in the centre to enable the root to act as an anchor

Question 36

Transpiration

Answer 36

Movement of water through xylem

Question 37

Explain the transpiration stream

Answer 37

The stream of water though the plants xylem caused by the loss of water through the plants stomata in the wind
Water evaporates through stomata
Water potential gradient between leaves and stem - water moves into leaves by osmosis
Water potential gradient between stem and roots - water moves into stem by osmosis
Water potential gradient between roots and soil - water moves into root hair cells by osmosis

Question 38

What makes water vapour diffuse from the inside of a cell into the air

Answer 38

Water evaporates from inside leaf into leaf’s air spaces
Concentration gradient forms between the air inside leaf and the air outside the leaf

Water vapour diffuses from the area of high concentration or the air inside the leaf, to area of low concentration of air outside the leaf

Question 39

Structure of stomata and how they open and close to control gaseous exchange

Answer 39

Stomata are made up of 2 guard cells

When there is plenty of light and water the guard cells take up water by osmosis and become turgid,
The inner wall of the guard cell is thickened so the cell curves as it becomes turgid creating a gap between the two guard cells,
This gap is known as the stomata,
If conditions for photosynthesis are poor then the guard cells lose water and become flacid,
When the cells are flacid the gap between them closes

Question 40

Explain why the upper surface of many leaves is covered in a thick, waxy cuticle?

Answer 40

To prevent uncontrolled water loss
In hot environemnts this layer is very think and shiny

Question 41

Calculate rate of transpiration

Answer 41

Calculate the rate of movement of an air bubble using a potometer
Rate of movement = distance (mm) ÷ time (s)

Only an estimate as small volume of the water taken up by the shoot is used in leaves and not transpired

Question 42

Why does the plants need for CO2 increase the rate of transpiration in a plant.

Answer 42

Plants need glucose for respiration
Glucose is product of photosynthesis
Photosynthesis requires carbon dioxide and water
Plant must open stomata to enable the diffusion of carbon dioxide into the leaf
Open stomata allows water vapour to leave the leaf via diffusion
Lose of water from leaf increases rate of transpiration

Question 43

State the factors affecting the rate of transpiration

Answer 43

Light intensity = increase light, increase transpiration
Temperature = increase temperature, increase transpiration
Air movement = increase air movement, increase transpiration
Humidity = increase humidty, decrease transpiration

Question 44

What ringing experiment shows

Answer 44

A ring of bark is scraped away that also removes the phloem, exposing the xylem
Sugar then attempts to move down the stem but is stopped by the ring
This is demonstrated by a bulge of sugar forms above the ring
Suggesting that sugar moves down the stem in the phloem and sugar transported by the phloem

Question 45

Explain how potometer experiment can be used to measure rate of transpiration

Answer 45

Set up potometer making sure the stem is cut under water to ensure no air bubbles
Release an air bubble into the capillary tube
As the water evaporates from the leaves and moves into the stem the bubble moves towards the plant
Measure how fast the air bubble travels
Refill and repeat the experiment

Question 46

Difference in veins and arteries

Answer 46

Veins - blue - thin - carry blood to heart - valves along the length - wide lumen
Arteries - red - thick - carry blood away from heart - thick walls - narrow lumen diameter

Question 47

Pulmonary artery

Answer 47

Heart pumps out deoxygenated blood to the lungs through this artery.

Question 48

Pulmonary vein

Answer 48

Heart receives oxygenated blood from the lungs through this vein.
Coronary arteries have the same purpose:
The heart muscle is supplied with oxygenated blood through these arteries.

Question 49

Vena cava

Answer 49

Heart receives deoxygenated blood from the body through this vein.

Question 50

Aorta

Answer 50

Heart pumps out oxygenated blood to body through this artery

Question 51

Pathway through human heart

Answer 51

Blood enters the heart via atria
Once filled with blood, atria contract, forcing blood down into ventricles below
When the ventricles contract, they force blood to exit heart

Question 52

What happens when ventricles contract

Answer 52

they force blood to exit the heart

Question 53

Why might someone be fitted with an artificial pacemaker

Answer 53

group of cells in right atrium act as a pacemaker to control heart’s beating -
If there are irregular heart rates, can be corrected using electrical devices known as artificial pacemakers

Question 54

Difference between transpiration and translocation

Answer 54

Translocation is bidirectional (movement is both up and down the plant)
happens in the phloem NOT xylem

Unlike water transport (transpiration) which is unidirectional

Question 55

Sample card

Answer 55

The heart muscle is supplied with oxygenated blood through these arteries.